Current readers for fluor-labelled diagnostic arrays (including 'gene chips') are adaptations of laser-scanning confocal microscopes. They have poor multiplex capability' and are ill suited to imaging grids on high-reflectance substrates such as glass and silicon. We propose to develop a fluorescence array reader (FAR) based on a novel imaging spectrograph capable of exciting and spectrally resolving multiple fluors simultaneously our initial goal is 7 fluors (combinatorial complexity 127'). The design will have a spatial resolution of a few microns. and exceptional immunity from substrate reflectance artifacts. It is ideally suited to imaging weak fluorescent signals on strongly reflective substrates. and will accommodate any array format, from coarse manually-spotted grids with millimeter feature sizes down to nanofabricated arrays containing 10(6) or more elements cm-2. The optical path contains no moving parts except the specimen stage, and no filters. Parallel multi-fluor signature analysis is done in a single pass. Detection limit at full resolution will be on the order of 100 fluor molecules mu m-1. The reader is aimed at 'next generation' diagnostic arrays, in which combinatorial labelling methods will permit simultaneous testing with multiple probes per spot of patient DNA, and analysis of pooled DNA from multiple patients using the same diagnostic array. PROPOSED COMMERCIAL APPLICATIONS: This research will develop an automated reader for high throughput parallel imaging and analysis of multi-fluor labelled diagnostic arrays for clinical and research laboratory use. Applications include simultaneous multi-gene analysis, expression profiling, high-throughput screening, and sequencing.